The invention relates to a method and a sensor for detecting occurrences of wetting on a pane, particularly a rain sensor for vehicles.
Rain sensors have optical measuring sections which contain a light transmitter and a light receiver. Light transmitters and light receivers are coupled to the inner side of the pane so that light emitted from the light transmitter is reflected onto the light receiver by total reflection on the outer surface of the pane. However, the light receiver is also exposed to the ambient light. In order to reduce the influence of the ambient light, two identical optical measuring sections can be used which are arranged adjacent to each other, with the differential signal of the light receivers then being evaluated. However, the modulation capability is limited by outside light and the asymmetry of the optical and electronic components.